Topic: CB 500/550 fork leg dimensions

[dragracer]

Can anyone tell me the length of the lower leg for a CB500/550? Measuring from the top edge at the seal down to the centerline of the axle.

I know the diameter of the tubes is the same as the 750. I need to get my dragbike project as low as possible in the front without raking the neck. I need to leave some clearance between the top of the fork and the bottom of the lower triple for fork travel. If the lower legs of the 500/550 are shorter than the 750, it would allow me to lower my frontend on the bike once the forks are shortened ( internally) to the limit. I'm not interested in putting a frontend on the bike with smaller diameter tubes but just want to know if anyone has an answer to the measurement of the lower leg.

Thanks.

[bwaller]

Same as 750's Frank. 

[754]

You probably mean the 750 K from 73-76 the 77/78 K is longer ..maybe same length as the 77/78 F forks.

[bwaller]

Sure the 77/78 year legs are longer for the 550 too.

[dragracer]

Hmm. I bought this particular setup advertised as a F1. So I assume that's what I have. I'll measure my F3 legs to compare the length. I wonder if the CB 450 legs are shorter. The diameter is 35mm as well.

[bwaller]

450 legs will be the same length as early shorter 750 K's as well.

[scottly]

The early 750 lower legs are about 12.5" from the top edge to the axle centerline, while the late 750 legs are about 14".

[dragracer]

I'll measure the legs on the project bike to see what I have now.

Thanks guys, its a starting point to eliminate some of my options to getting the front end of the bike lower.

1) shorter fork legs- seems like there is a difference in early and later 750's. Will explore others.
2) use a 17" front wheel- good option but the wheel is 3.5" wide, tight fit inside the forks with a rotor. Have 2 on hand. 
3) rake the neck- a workable option but it increases wheelbase from the front. Not my preference.
4) move the neck up/ short neck - can be done with an aftermarket neck. Would lower frame on trees without raking neck or increasing wheelbase. More work and expense then I want to expend.

[bwaller]

Do you add a spacer on the damper rod? It shortens installed height but obviously travel as well.

[754]

Will not the tire be the limiting factor, not the length of the forkleg ?

[dragracer]

I added spacers under the dampner to shorten them to my initial length for mock up. As you can see, I pulled the forks up in the trees at the minimum travel I'd need between the lower tree and fork legs. Its about 3" I will need to compensate for when I add additional spacers. Still, it might not give me the proper ride height. The forks are stiff so I'm allowing some compression for the weight of the engine etc.. Again, I'm looking at options to put into place in case the weight I'm adding doesn't bring it down more. I'm going to tack up the shock/ pivot mounting points, put the roller on the ground and drop a dummy engine on the frame to see exactly what I have as far as ground clearance and fork travel.

[gschuld]

Cb500/550 fork TUBES are shorter than the cb750 tubes.  By +/- 1.25" I believe.

George

[dragracer]

Cb500/550 fork TUBES are shorter than the cb750 tubes.  By +/- 1.25" I believe.

George

Upper tubes are shorter or are the lower legs shorter??

[gschuld]

Upper tubes.  Not your issue though.  I see, your problem is that you can't get it lowered enough without having too short of space for travel before your lowers and lower trees contact. 

George

[Old Scrambler]

Frank..........CB350 twins (also CL) appear to have shorter legs. CYCLE-X sells new fork tubes in shorter lengths.